This invention relates to wheels for vehicles.
The invention is concerned with disc wheels or demountable rim assemblies of the kind comprising (1) an asymmetrical rim having first and second axially spaced bead seats separated by a well and a ledge between the first bead seat and the well and (2) a disc or an adapter band welded to the rim. The ledge is often, but not always, generally cylindrical.
If the rim has a disc welded thereto then the rim and disc form a disc wheel which is hereinafter referred to as "being of the kind specified". If the rim has an adapter band welded thereto then a demountable rim assembly, hereinafter referred to as being "of the kind specified", is provided, the rim assembly being such as to be capable of being releaseably secured to a hub. Disc wheels and demountable rim assemblies of the kind specified are widely used with tubeless tires.
In our patent application, Ser. No. 822,512, filed Aug. 8, 1977, we claimed a disc wheel or a demountable rim assembly of the kind specified wherein the disc or adaptor band is T-joint fusion welded to the radially inner surface of the rim adjacent to the transition from the first bead seat to the ledge so that the axially inner edge of the disc or band adjacent to the well is located within a distance B/5 (as therein defined) of the transition between the ledge and the first bead seat.
At the time that application was filed, certain standards for wheel manufacture were in existence, as illustrated, for example, by the table in FIG. 1 of the earlier application. Since that time, however, modifications have been made in some wheel standards in respect of the defined minimum bead seat length and it is the purpose of this continuation in part application to disclose the applicability of the present invention to wheels made either to the original or the modified wheel manufacturing standards, and to claim the invention with respect to such wheels.
When a rim of a disc wheel or assembly of the kind specified carries an inflated tire the rim is subjected to forces which cause an overall axial tension stress in the rim, i.e., parallel to the rotary axis of the wheel or assembly, and additional differential stresses in the radially inner and outer surfaces of the rim which are caused by bending of the rim section.
We have found that the overall stresses in the rim section due to an inflated tire are lower in that part of the rim section containing the first bead seat and the ledge than they are in the part of the rim section containing the second bead seat. As a result of our investigations we have found that there is an optimum position at which to weld the disc or adaptor band to a rim in a disc wheel or demountable rim assembly of the kind specified so as to have low stresses, and an absence of steep stress gradients, in the rim adjacent to the welds.